Characterisation of optical properties in micro-patterned InGaN quantum wells

Optical resonance modes of micro-scale patterned InGaN quantum wells including disks and rings of various diameters (0.5-20 μm) have been investigated. For the observation of resonant modes, well-defined features and striation-free sidewalls were essential. Each of the patterned structures displayed resonant modes superimposed on the main InGaN photoluminescence peak. The large number of such modes observed has allowed analysis of the mode spacing as a function of both wavelength and diameter. Comparison with a simple model has confirmed that these are whispering gallery modes. No evidence of radial modes was observed. Microrings showed fewer optical resonance modes than microdisks. In addition, the number of observable modes correlated with the width of microring structures.